Radio echo apparatus



Sept. 9, 1952 R. M. PAGE RADIO ECHO APPARATUS Filed NOV. 17, 1942 2 SHEETSf-SHEET 1 m5313131li ge-E'- fffzj R. M. PAGE RADIO ECHO APPARATUS Sept. 9, 1952 2 SHEETS-SHEET 2 Filed Nov. 17, 1942 ROBERT M. PAGE 7/ @gi-J4 www Patented Sept. 9, 1952 UNITED STATES PATENT OFFICE 2,610,319 f RADIO ECHO APPARATUS Robert M. Page, Washington, D. C.

Application November 17, 1942, Serial No. 465,919

y 1c claims. (o1. 343-11) (Granted under the act of March 3, 1883, as

This invention relates to radio echo apparatus and more particularly to systems for detecting the presence of remote objects included Within a field extending 360 about a reference point and for producing a visual plan position indication of such area, or any preselected portion thereof, whereon indications of detected remote objects are produced in such a manner as to lsimultaneously show range and direction thereof with a high degree of accuracy.

Radio echo apparatus disclosed by the prior art include a directional beam antenna from which equally spaced energy pulses are emitted at a constant rate, and an indicator, such as a cathode ray tube, upon whichv a time sweep is impressed in synchronism with the energy pulses emitted from the antenna. When the emitted energy pulses impinge upon remote objects, echo pulses are reflected from the` objects and applied to the indicatorin such a manner as to produce an indication 4on the sweep which portrays a measurement of range of the object from which the echo pulse is reflected. In the prior systems directionalindications of remote objects detected in the foregoing manner are derived from the angular position of the directional beam antenna. Directional indications obtained in this manner are not of a high degree of accuracy since the directional beam necessarily has a substantial width, -approximately equal to an arc of l to l5 degrees, and therefore echo pulse indications are produced on the indicator whenever a remote 'amended April 30, 1928; 370 O. G. 757) object is included within any portion of the beam.

Consequently, it becomes necessary to continually adjust the antenna bearing until echo pulse indications of maximum amplitude are produced, in which case itis assumed that the center of the beam, the lportion thereof having maximum power, is directed toward the object, and that the antenna is likewise pointing directly toward the object. The foregoing operations are difficult to perform rapidly with a high degree of accuracy and therefore the prior systems are only capable of producing approximate indications of direction of remote objects.

From the foregoing it can be readily seen that numerous difiiculties arise'when attempting to determine range and direction of a remote object with a radio echo system of conventional construction. As mentioned heretofore, directional indications, when obtained, are not of a high degree of accuracy, and furthermore, it is extremely diilicult to obtain a directional indication of a remote object which corresponds to a remote object indication on the indicator, since means for obtaining range and bearing are isolated, distinct devices. The foregoing defects are more readily comprehended when attempting to determinerange and direction of all remote objects included within an areaV extending 360 2 about the apparatus. It is necessary, in the latter instance, to slowly rotate the antenna by small increments throughout 360 and to con--y tinually record echo pulse indications appearing on the indicator for each position ofthe an,.- tenna. In view of the fact that extremely tedious operations are required to obtain ausubstantially accurate bearing Vindication of a single remote object, the fallacies of the foregoing method are obvious, and the same becomes impossible in instances wherein the remoteobjects are moving at high velocities, such as aircraft for example.

It is therefore an object of the present invention to provide a novel method of indicating range and direction of a remote object.v Y

Another object is to provide novel means lfor indticating range and direction Vof a remoteob- Jec Another object is to provide novel means fo `rapidly indicating range and direction of a plurality of remote objects with a high degreepf accuracy. 1 lr Another object is to provide la radio echo'ap'- paratus capable of detecting all `remote objects included within a field extending '360 about the apparatus having novel means for producing 'a visual plan position indication ofany preselected portion of such field.

Another object is to provide a radio echo'apparatus having means for producing a plan position indication on an indicating area, suchas the screen of a cathode ray tube, of an area extending 360 about the apparatus which" portrays measurements of range and direction of all objects included vvithin such area, including novel means for lcentering only a portion of the plan position indication on the indicating area and for expanding such portion to increase the accuracy of the range anddirectional measurements provided thereby. Y

Still another object of the invention is to provide a sweep circuit for producing a rotating radial sweep of the electron beam of a cathode ray tube including novel means for varying the point about whichthe sweep rotates. .1

`Still another object is to provide a sweep circuitV for producing a rotating radial sweep of the electron beam of a 'cathode ray tube wherebya rotating radial trace is produced on the tube screen, including novel means for Varying the point about which the sweep rotates and means for expanding the sweep in such a mannerthat thetrace extends to the periphery of the screen notwithstanding the position of the point` of rotation. i

Stillanother object is to provide a radio echo apparatus including means for producing,` on the receiving screen of a cathode ray tube,'a plan position indication of an area extendingf3609 about the apparatus whereon rangev and directional ir,:dicaddons:v ofalliremote objects included in sucharea are produced, and including novel means for producing an expanded plan position indication of any preselected portion of such areafrom which measurements of range of-remotefobfjects included within such preselected portion are indicated with a high degree of accuracy;

Other objects and featuresof. the; invention.

will appear more fully hereinafter from the fol'- lowing detailed description when consideredI in;

connection with the accompanying drawings which illustrate one embodiment-of' the invention..

, 4 l of the screenvthat is a direct measurement of range of the "remote obiectzlfromiwhich the echo pulse reflected; while" therv angular "direction of the radial sweep, at the instant an echo pulse indication appears thereon, is the direction or azimuth; angle of the remote object from which the echo pulse is reflected since the directional pulse-energyfemission and the radial sweep rotateinsx I-nchronismL Furthermore, a system constructed in accordance with the aforementioned application not only functions to produce a plan positionx indication. of remote objects included Witliinaieldv extending 360 about the apparatus,

form;` of a radio echo apparatus embody- 'ingftl yprinciples of the present-invention 2i sfa--showingfof the viewingyscreen ofA the cathode raytube indicatorn disclosedin Fig: 1 wlth'af'vi'sualplan position indicationof an area extending throughout 360 about a reference 'p'ointf yproduced thereon;v

Figs'Bf is an illustration of thel viewing: screen of the cathoderaytubel indicator having any expanded? visuali plan position indication produced thereon`v of an area extending: through lessfthan 360, at a certain angular position, and

' Illgzfltfis' an illustration'v of?` the: viewing screen ofthe cathodeL ray tube indicator having an- `ex- "panded visuali plan position indication produced thereon of an area extending through less than 359"at, axrfangular position different". fromz the singular-'position of then-indication shownin-Fig. 31

Im-thee application: of:y Robert: M.4 Page; Serial Nozlrzigled August 21, 1942;,.for Radici Echo v Almaratlw; aesystemi isA disclosedfcr detectingi the presence of al1 remote objects. includedwithin. a diextending 350 about vthe apparatus andV for mducnga, vlsuallplan positionindicationWherendicationsi of; detected. remote objects are Shuwmat: certain: radial andl angular positions Withzrespeciita' a reference pointirespectivelyfA in accordance: withthef range; and direction of: corresponding: remote: objectsv withV respectto: the apparatus;k More; particularly, means are. providedfby'the aforementioned' application for pro.-

"duclng: a highly: directive pulse, energy. emission whichisecontinually vrotated for scanning an area V"extending .360 about the apparatus so that energlli pulses arereected from alll remotey obiectstincludedwithin the scannedareain the form off'echoxpulses, meansfor producing-aradial sw-eep off the; electron beam of* a cathoderay tubein synchronism` with thel pulse energy emission,

frneans for-rotatingI the radialsweep in synchronisnnwithrotation of the'directional pulse-energy emission andmeans forfreceiving the echo pulses and' applying the latter to -the cathode raytube insuch a: mannen as. to vmodi-ilate-the intensity f of theeelectronf/ beam to-lproduce a visual indication Joni thea cathode ray tubeA screen. With an apparatusnof the; foregoing, character avisual plan "positiony indication isf produced on'` theviewing screen of the cathode ray tube. Since emission of energia Dulsesfisaproperly synchronized-with-.radial :rangement-,off the electron beam the echo` pulse intlicatilirns.:pr.oducg-idcon; the; screen appear onthe r'lah meen, a certainl distancefromi theL center but is also capable of v.producing a continuous indication of a single-remote object at a fixed bearing aswell as-producing a plan position indication of' any' preselected section off thel area extending 360 about-the=apparatusz ItA is contemplated by thepresent-invention to provide novel meansA in connection with a radio echo apparatus having the'- foregoing: characteristlcsforproducing an expanded plan position indication of-any preselected portion off the` area extending 360V about theapparatus so that rangeand directional indications` off remoteobjects f ineludedy within thepreselected area arereadily obtainedv with an extremely high degreeof accuracy. More particular-ly, means" are provided bythe presentv` inventionv for varying the-'point about* which the radial sweep of= the electron beam rotates to any position within or-v outside the cathode ray' tubescreenand means fon increasing; the length of thel'sweepv so that the entirediameter of i the screen= isutilizedl for indicating range-'in apreselected direction. With an: arrangementL of the foregoingtype the-lengtlfll of," the sweepline may be increased'V from the normali length thereof; Whenr the latter rotates about the centen of the cathode rayctube-l screen, to` approximately fourtimes` as; great, forV ex'- ample; during the same period'A ofjtime sothat units ofA range for a-certain length of'. the sweep line are' increased" indirect proportion, thus increasing theV accuracy ofv the indications byv a corresponding; degree.

Withreference more' particularly to' Fig, l of the drawings, a radio echo'apparatus embodying the principles of the present invention isv dis: closedY therein including`4 a rotatable directional' beamz antenna I0. constructed inv any suitable manner for-producinga highly directive beam of energy, a radiofrequency pulse transmitter Il andA aK radio frequency pulse-receiver l2; Transmitter Il andgreceiver |-2have connections withantennav I0 through duplexing circuiti |3which automatically functions to formA an individual' connection between transmitter ll and antenna` I0; and an individual connection between thev antenna and receiver' l2 Vfor enabling a single antenna to be utilized for transmission' aswell' asv reception. Transmit-ter H is designed in such a manner asto respondto operation of electronic keyerA I 4 to emit radio frequency pulses ata predetermined rate, while/receiver I2? is' of`such construction as to receive and properly amplify` echo pulses produced whenV the transmitted .radio pulses impinge upon"v and reiiect from. remote objects. Transmitters and' receivers of the type: employed inconventional television systemsare suitablefor-thesefpurposes'. 'Ihe radio echo ap'- paratus further' includes a-suitabl'e-indicator l5; which maytake the form. of acathoderay tube as: shown,A upon which indications' of' reception ofr echo i pulses:- at; receiver: |2';v are producedz.. In' orden` to'. producer. echo-1 pulse.-y indications oirin:-

5 dicator tube I5 as a function Vof range of remote objects, a suitable sweep circuitisprovided for sweeping the electron beam thereof, while synchronizer I6, which controlsA operation of the sweep circuit and electroniclkeyer I4, Vis included for properly synchronizing theradio pulse .output of transmitter II and the sweepof the electron beam. The sweep circuit is shown as a schematic circuit diagram enclosed by broken lines A-A in Fig. l of the drawings, and is referred to throughout the following description as sweep circuit A-A, the construction andioperation of which will appear more fully hereinafter. The apparatus is adjusted in such a manner that the electron beam initiates `movement in a certain direction at the instant a radio pulse is emitted fromv the transmitter. Sweep circuit A-A functions to sweep the electron beam-at a constant rate for a certain period of time following initial movement and for rapidly returning the electron beam to the original or normal position thereof prior tol emission ofthe next radio pulse from the transmitter. When the` pulse from transmitter II is emitted from antenna II) in a direction as to impinge upon a remote object an echo pulse is reflected from such object, received at antenna I and passed to receiver I2.V The echo pulse is suitably amplied at the receiver and then applied to the indicator tube I is such a manner as to modulate the intensity of the electron beam to produce an indication on the sweep of the application thereof. The indication of the echo pulse appears on the sweep a certain distance from the originating point thereof that is a direct measurement of range of the remote object from which the echo pulse reiiected, with respect to antenna I0.

As mentioned heretofore, the radio echo apparatus disclosed in the aforementioned application includes means for rendering the apparatus capable of detecting the presence of all remote objects included within a field extending :360 about the apparatus and for producing a visual plan position indication of such detected objects, with the indication of each object so characterized as to simultaneously show range and direction thereof. As shown in Fig. l, motor I'I is provided for continually rotating antenna I0, by means of shaft I8, to continually scan an area extending 360 about the antenna with the highly directional pulse energy beam emitted from the antenna. As will appear morefully hereinafter, sweep circuit A-A is designed in such a manner as to radially sweep the electron beam of the indicator tube I5 whenever an energy pulse is emitted from transmitter II, and to respond to the output of variational bias supply I9, which operates in synchronism with rotation of the antenna, through shaft J, in such a manner as to continually radially sweep the electron beam in a direction corresponding to the direction of pulse energy emitted from the antenna. The construction and operation of variational bias supply I9 is described more fully hereinafter.`

With the foregoing. arrangement, the electron beam of the cathode ray indicator tube is radially moved in a direction corresponding to the bearing of antenna Ill, that is, in the direction that the normal axis of the antenna is pointing, whenever an energy pulse is emitted. The radial movement of the electron beam produces a trace on the cathode rayindicator tube screen that originates at the center of thescreen and moves toward the periphery thereof in a direction corresponding to thev direction the normal axis of 6 y the antenna is pointing, and consequently, since the normal axis ofthe antenna passes through the portion of the directional energy beam having greatest power, the trace moves in a direction that energy of greatest power is emitted. As will appear more fully hereinafter, the intensity of the electron beam is biased in such a manner that the trace produced on the screen is normally invisible; however, when energy, such as' an echo pulse or a noise signal, is applied to the cathode ray tube the intensity of the electron beam is modulated in such a manner as to render the trace visible at the instant the energy is applied. Therefore, visible indications are produced on the screen, whenever echo pulses are applied to the cathode ray tube, each of which occupy a certain radial and'angular position with respect to the center of the screen respectively in accord ance with the range and direction of the remote object, with respect to the antenna, from-which the echo pulse reiiected. The foregoing isrmore readily understood with reference to Fig. 2 of the drawings wherein screen 2| of indicator tube I5 is shown with radial traces 22, 22a, 22h, 22a-:and 22d, produced thereonat various angular positions corresponding to similar angular positions of antenna I0 as the latter rotates through a complete revolution, and with echo pulse indications 23, 23a, 23h, 23e, and 23d, produced Von corresponding radial traces at various radial distances from the center o of screen 2|, in accordance with the range of remote objects from which the echo pulses reflected. It is to be expressly understood therefore, that with a visual plan position indication having the foregoing characteristics, range and direction of all remote objects included Within an area scranned by the directional energy from the antenna are simultaneously shown on the screen by a single indication of each remote object. The range of the remote objects is given by a direct measurement of the radial distance from the echo pulse indication to the center` of the screen, while the direction of remote objects corresponds to the angular position of the: radial trace at the instant an indication is produced thereon. j

With reference again to Fig.l 1, the cathode ray indicator tube I5 is of conventional design including a pair of` horizontal and vertical deection plates and means for generating a beam of electrons, while sweep circuit A--A is constructed in accordance with the aforementioned application and functions in such a manner asto simultaneously apply push-pull saw-tooth wave forms to each pair of deflection plates and to respond to the output of variational bias supply I9 to vary the phase and amplitude of the sawtooth wave forms in such a manner as to apply the proper voltages t0 the deflection plates whereby the electron beam is continually radially moved, upon simultaneous application of saw-,- tooth wave forms to the deflection plates, in a direction corresponding to the bearing of an-r tenna IG. More particularly, sweep circuit vAK-A includes a pair of channels, one of whichsupplies the horizontal deflection plates H1 and H2'of the cathodey ray tube, While the other channel pro--` vides the proper voltage to vertical deflection plates Vrand V2. Hereinafter, each of the channels is respectively referred to as horizontaland vertical channels, as shown in the drawing. Also, similar elements of each of the channels have similar reference numerals, with primed numerals designating elements of the horizontal channel. The first stage of the vertical and horitube 24' bylway of conductors 84, 85 and resist-y ances 93 and 9|'. Y

Anodes 29 and 39V of tube 24 are connected 'together and the outputs of the tube are passed through common condenser 86 to point 81, while the outputs at anodes 29' and 39' are applied through condenser 83 to point B1'. The sinusoidally modulated saw-tooth wave forms simultaneously applied to point 81from anodes 29 and 39 produce a resultant voltage at point 81 which comprises saw-tooth wave forms swinging symmetrically across a line of zero potential, the amplitudes of which are 100% sinusoidally inodulated through a complete sinusoidal cycle upon each complete revolution of antenna I9, with the saw-tooth generated during the half the sinusoidal cycle being 180 out of phase with` respect to the saw-tooth wave forms generated during the other half sinusoidal cycle. The resultant voltages appearing-at point 91', for a similar complete revolution of the antenna, are similar to the `aforementioned resultant voltages appearing at point 81, however, for reasons mentioned heretofore, the voltages appearing at points 81 and 81' are sinusoidally modulated in quadrature.

Points 91 and 81 are respectively' connected to grids 88 and 88 of duplex vacuum tubes 89 and 89' each of which comprise the second stage of the vertical and horizontal channels, respectively. The eathodes of tubes 89 and 99 are connected through resistances to ground, while anodes 95, 9| and 99'., 9|' Yare connected to points 92, 92 sof positive potential in push-pull relation by means of resistances 93, 94 and 93', 94'. Tubes 9 and 89' are biased for class A operation so that the potential at anodes 99 and 99', and the potentials across resistances 93 and 93', ccmprise saw-tooth wave forms which swing symmetrically across the average positive potential applied to the anodes from points 92` and 92', the amplitudes and phases of which vary in a manner corresponding to the varying phases `and amplitudes of the resultant voltages appearing at points 8".' and 91. The voltage `outputs of anodes 99 and 99' are fed by Way of resistances 93, 93 and condensers 95, 95 to the other grids 96 and 96' of tubes 89 and 89' respectively. The connections from resistances 93 and 93' are adliusted in such a manner so that the voltages applied to grids 96 and 96 are respectively equal to the voltages applied to grids 99 and 89. With the foregoing arrangement, tubes 89 and 99 produce push-pull saw-tooth outputs, With the sawtooth wave forms swinging symmetrically across the average anodepotentials, with the amplitudes of the saw-tooth wave forms 100% sinusoidally modulated, 180 out of phase at the anodes of each tube, through a complete sinusoidal cycle upon a complete revolution of antenna I9, and with the saw-tooth wave forms produced during one half the sinusoidal cycle being 180 out of phase with the saw-tooth wave forms produced during the other half sinusoidal cycle. Also, the reasons mentioned heretofore, the push-pull outputs of tubes 99 and 99' are in quadrature with respect to each other.

The outputs of anodes 99, 9| and 99', 9| are applied through individual modulator stages to deflection plates V1, V2 and H2, H1, respectively, of the cathode ray indicator tube l5. The stages associated with the vertical deflection plates in` clude screen grid vacuum tubes 91 and 98 connected in push-pull relation. Screen grids 99 and |99 of tubes 91 and 98 respectively, are connected together at 'point |9| andare maintained at positive potentialbya suitable; source |92 applied thereto, while the cathodes ofV the'tubes Vare con-1 nect'edftogetherV at point |93 Which is maintained at afsuitable potential, by battery |94, for Class A operation of the tubes. Anodes and |96 are connected to point |91 of positive potential1 through resistances |98 and |99, while the anodesare also respectively connected to verticalde-f the tubes are respectively connected through con-. densers||2 and ||3 to anodes 99 and9l of tu'be 99 in order to vary the outputsof tubes 91 and" 93 in accordance with the push-pulloutputof tube 89. The modulator stages between anodes primed numerals similar tothe-numerals designating corresponding elements and associated circuit elements of tubes 91 and 98.

The grids of modulator tubes91, 98, 91' andV 96' are also suppledwith a source of sinusoidal varying direct current bias, from variational bias supply I9, for sinusoidally varying the aver'-v age. potentials at anodes |95, |96, |95' and |96', for a purpose that will appear more fullyVA here-` inafter. VThefmeans included in variational bias supply .I9 for supplying the bias to the grids' of the modulatorl tubes comprises rectifier tubes '|15' and H6. Thecathodes ||1 and ||`8 of tube '|5 are connected to the end terminals of secondary winding 56 of transformer 52, while cathodesl I9 and |29 of 'tube ||6 are connected to the fend terminals` of secondarylwinding 69 `of transformer 55. Anodes .|21 and`|22 of-tube ||5 are connected to ground` through condensersV |123v and |24, respectively, each *of Whichare shuntedby resistance |25 and |26, while anodes |21 and |28 of tube H9 are connected to condensers |29,H |39 and resistances |3I, |32 in a similar mannen' Direct current. sinusoidally varying voltages ap pearacross resistances |25, |26, |3|, and |32i.- which respectively' correspond to the voltages`-` generated across resistances 68, 69, 14; and15`,

for reasons mentioned heretofore relative to generation of the latter voltages. age across resistance |25 is applied to grid ||9 of tube 91 through lead |33 and resistance |34, While the voltage produced across resistance |26 is fed, by Way of conductor |35 and resistance |36, to grid l|| of tube 98, and the voltages gen#-v erated at resistances |3| and |32 are respectively applied to grids Ill' and H9 of tubes 91 and- 98' through conductors |31, |38 and resistances'4 |34', |36. Since tubes 91, 98, 91 and 98 are biased for Class A operation the voltage-outputsappearing at the anodes of each of the tubes comprise saw-tooth wave forms swinging sym-A metrically across the sinusoidally varying anode potentials, with the amplitude of the saw-tooth` waveforms 100% sinusoidally modulatedY through a complete sinusoidal cycle uponve'acli The saw-V tooth wave forms generated at each anode dur--4 ing one half a sinusoidal cycle are out of`- phase with the saw-tooth wave forms'generated" at the anodes during the Aother half sinusoidal4 cycle, while the saw-tooth wave forms at anodesV |95 and |95' are at all4 times 180 out of phase.; with respect to the saw-tooth wave forms ap4` pearing at anodes |96 and |96', and the,output,v of tubes 91' and 99 are sinusoidally modulatedin. quadrature with the output of tubes 91 and 99."

complete revolution of antenna |9.

The output volt- 1 1 '.Iii. outputs .et-apodos 1.195, 106,105' .and` i067. espeotiveiy applied toV deiieetion plates. Vi. italiana@ H1 for supplying. the proper voltaeoe between the. `deflection plates to. sweep` the eleotron beam of the cathode ray tube in a direction pending to the bearing of antenna I0, whenever saw-tooth wave forms are simultaneouslyapplied to. the deection plates. By applyiiis the sinusoidal varying direct current biases to grids l ,..|I ll,... H0' and |||v in the proper phase relation with respect to the phase and sinusoidal @trying amplitudes of the saw-tooth wave forms 21.0.epiled'tothe.grds. and by properly adjustthe. Value, of suchbiases, the electron beam imintained equally-distant from the deec. tigt; Plates, i. e., atthe center of the screen, at the. the.. saw-tooth wave forms originate. with the..foregoinggarrangement, the electron kennis ont. from the center of thescreen, upon simultaneous application of.l saw-tooth wave Immetti the` deflection plates, thus producing. a

radial sweep which rotatesabout a fixed point in Smehronism with rotation ofantenna 0.

mchronizer.. I6 is connected to wave genelator .3.5 in order to control. operation of electronic keverv I4v and sweep circuit. A-A in the aloresadfmanner so that sawetooth waveforms, andconseuuentlv. radial. movement of, the. elec.-v tinILb. om, `are produced insynchronism withthe Tadidpfrquency pulses. attransmitter. Il. The, @Impulsen amplied at. receiver. 2 are passed tnroughpoupling condenser. |39 to grid |40 of the cali-'linde ray. ,tube 'to modulate the intensity of.

theeletmn beam. Bias. supply |4| is also. con.- Iletitto grid .Muto control .the intensity of the.. election beam. The. biasVv supply is adjusted in Such @manner so thatthe electron beam normally @5 not.. produce a visible trace. on the. 'screenV dndstliereore, only indications of noise signalsv andi eliopulses applied. to. the gridare'seen. This. arrangement. greatlvfacilitates observations,

esileally Whenthe radial sweep is rotating at a rate. .of. speed. The apparatus disclosed 11,12 Operates in a^ mannerjfully described heirgiotol'e .to produce a,A plan position indicationv 9.`;..i'11!4tr2.fted,n Fig. 2 of'the drawings.'

AASellievifiu'sly. mentioned, 'it is anobject of the present .,riventionto providenovel means for cen.- teruigionlvaportion of .the plan positionindioa- .tlQI1,.0I1..the,S.Qreen. With the portion correspondilitmapledetermined.sectorof the scanned area, at..argiy;angulal.gpositionabout the apparatusand oth thiplan.pQSiQnndcation insuch a manner so thattheame .covers a substantially greater. area of theporeem With a radioecho .apparatus havlng he, foregoingmeansrange. and directional in ationsfofv all remote objects includedwithin t-lieg,preselected` sector areobtained with high.

degreeszoflaccuracy, substantially greater' than tneaguracy of theindications providedwhena Plan. positiony indication. of the area extending.. 3fm?, about ,thev .apparatus is produced, as shown l Witniurther reference to Fig.. 1 .ofrthedrawinge.` and.. ,more i particularly to variational Vbias Stipplvl9thef0regcing means comprises potentimental deiiection plates,.respe.c.tive1y .byvarye c d thebiases 0,11I grids ||0., lll, H01 and Pn tiozneter device. .|50 includes resistances ,|52-

j.' 5.-; lfYmtheppDOSte.endSthereOf connecte l ed ogetljier. as snownand variable contact meni- .beg .154, and! Sii-.respectively .assoeiatedwitnree vel means for expandingsucnportion of:

urrentyoltages applied .t the .vertical and;

12 sistanoes |52 and |5.3. and respoetivelyooiineetedto resistances |25 and |25. 'Potentiometer device |514 is. similarto device. l@ arid includes resistentes |55 and |51 having variable contact members tia.. and |59. respectively ooiineoted to resistanees |31, and 13.2- Correspondine ends oi resistanoes i535 and |56 are connected together, and are supplied withv voltage.v of opposite polarity through. Suitable connections with batteries |60 and IGI; .Whenvariable contact members |54., |55, |,5 8 and |59; are equally distant from the ends of the. resist-v ance associated therewith. no additional potentiel. is applied tcresistances. |25, i216, 1.3 l. and. lattanti. a Sinusoidaily varying direct cur-rent bias is `apfplied to gridsV H0, llfand IV that swingsv across. an average direct current Voltage valiiede.-Y termi-ned by. variational bias supply |9. Ilovvevei,v when variable contact membersv |.54f and: 5,5; are. moved in synchronism to the rig-ht, as viewed in. the drawing, a. bias, of a certain polarity, and of-a4 value determined by the extent of -rnovementorA contacts |54 andl |55,.is applied to resistanceIZi,

whilea bias of equalvalue and ofopposite polarare applied to resistances |25.; and |.26ythesinus-- oidal varying direct current voltages appliedv to. grids ||0 and swingl across unequal average.; direct currentvoltage valuesi In 4instances where. in contacts |,54-and 55am-.moved in the opposite,l direction, to theA left as/vievved` in the drawing, the biases applied to resistances |25and |26` are. of the opposite polarity from. the bias. applied; when the contactsI arernoved.` in the other, direcf,V tion. Potentiometer-device|51 operatesinasimie. lar manner to'vary. the. average directcurrent; Voltage values acrosswhich thes-nusoidal varyingdirect currentV voltages. applied to grids.- Hi."t and ,l l". swing. When Athe sinusoidal.varying-di... rect current biases applied to grids H0, |||lv and. are varied inthe foregoing manner, the. sinusoidallyyarying average direct current volte.. ages across ,-which thesawftooth waveforms-an. plied to the deflection plates symmetrically swing, are variediri a. Corresponding manner. Theref.. fore, Wth.the.foregoing arrangement, when contact members` |54, |55,7|56. and |51 are;at the mid-points vof associated resistances, the originat. ing Vpointsof thesaW-tooth Wave forms. appliedto. the deflection platesare maintained .at equal, potential valuesandfa radial sweepfof the. electron beam is. produced upon simultaneous application of saw-toothv Wave v.forms .to the .deection plates, which rotates. about thev center Vof the screen-.vin synchronism wthrrotation ofantenna I0 infa manner described .heretofore and illustrated. in- Fig. 2. c However,when theaverage direct currentl voltages across whichthe sawetootnwave. formsl symmetrically swingy .arevv maintained .at different f Values at 4eachof the vertical Iand, horizontal ide,e flection plates, upon movement of contacts |54;A |55. |58 and Il 59; theaW-tooth: `wave .forms ap..v plied tothe deection plates originate/.atfpoints.y ofAvunequal potential and. Vthesvveep. `of the eleetron vbeam rotates about a Tpoint .remote .from thel center A.of the screen determined by thepositionsI of variable contact memberslt. |55, liizzand-V Theforegoing ismOIereadiIy understood. with."

reig'erencetofliigs. ..3 arid-4.0il the ...drawings Where.

tentiometer device |50 is operated insuch a manner that the saw-tooth wave forms applied to vertical deflection plate V2. originate at a potential value suiiiciently greater than the potential value of the saw-tooth wave forms applied to vertical deflection plate V1 to maintain the electron beam` at point o', as shown in Fig. 3, at the instant the saw-tooth wave forms originate. The length ofv the sweep of the elect-ron beam is `then expanded, by increasing the amplitude ofthe saw-tooth wave. forms upon operation of amplitude control |62 of generator 35 as shown in Fig. l. AThe amplitude of the saw-tooth wave forms is increased a suflicient amount so thatthe electron beam iszmoved the entire distance toward the periphery of screen 2|. As shown in Fig. 3, the expanded radial sweep rotates about point ic in synchronism with rotation of antenna l0, and the sweep traverses screen 2| only during a limited time as the same rotates throughout 360. Echo pulse indications are 'only produced on screenV 2| of remote-objects included within an area. about the antenna that corresponds to the area of screen 2| with respect to point o. From Fig. 3 it can be seen that the sweep line is expanded to approximately twice the. normal length thereof shown in Fig. 2. Since the amplitudes of the saw-tooth wave forms are in-A creased to expand the sweep, the time of the sweep, remains constant and therefore the accuracy of range indications obtained from echo pulse indications 23, 23a and 23d increases directly proportional to the increase in'length of the sweep.

In Fig. 4 the sweep is shown rotating about point o", outside the screen, and expanded a suicient amount to provide a moreaccurate indication of the remote `object represented by echo pulse indication 23e'. In order to maintain the sweep rotating about pointe" potentiometer device |50 is adjusted-so that the saw-tooth wave forms applied to vertical deilection plate V1 originate at a higher potential value than the saw-4 tooth wave forms applied to vertical deiiection plate V2, while device |5| is operated in such a manner to vary the biases applied to grids H0 and so that the saw-tooth Wave forms applied to horizontal deflection plate I-I2 originate at higher potential values than the saw-tooth" wave forms applied to horizontal deflectionplate I-Ii. The sweep is expanded, upon adjustment of control |62, a sufficient amount `tov utilize the entirexdiameter of screen 2|. Since the sweep is expanded approximately four times the length thereof shown in Fig. 2; the accuracy of the range indication obtained' from echo `pulse indication 23c is increased a corresponding degree. In order to produce the indicationshown in Fig. 4, antenna l0 is continually rotated through angle 0 to continually scan a certain angular area in which the remote object represented by echo pulse indication 23o is included, and the.

' Y sweep of the sweep of the electron beam thereforenecessarily rotates about pointe" thro-ugh an equal angle 0. By operating the4 apparatus inV the above manner `extremely accurate range and` directional indications of preselected remote ob-v jects are obtained without unnecessary use ofl power. The sweep of the electron beam is shown. rotating through 360 in Fig. 3, however this lllustration is for purposes of clarity only and does not necessarily represent a preferred mode of operation. i

In operation of a radio echo apparatus constructed according to the principles of the present invention, potentiometer devices `|50 and IBI.

114 Y the soriginatingpoints vof thesaw-tooth Wave, forms applied to the deflection plates at equalv potential, and antenna I0 is continually rotated through 360 whereby echo pulses arererlected from all remote `objects included within the areav scanned by the directional pulse energy emitted from the antenna. Since the electron beam of the cathode ray indicatory tube I5V is radially. swept in synchronism with the directional pulse energy emitted from the antenna and sincethe radial sweep rotates in synchronism with rotation of the antenna, a visual plan position indication of` the area extending 360 about the ap. paratus is produced, as shown in Fig.` 2. When it becomes desirous to obtain a more accurate indication of range and direction of any remoteobject corresponding to a certain echo pulse indication on the plan position indication, potentiometer devices |50 and |5| are adjusted to move the point of rotation of the radial sweep to any desired position in a direction substantially opposite the selected echo pulse indication,y

and the sweep is expanded upon operation. of manual control |62 so that the electron beam moves across the entire diameter of screen 2|,A

in a manner shown in Figs. '3 and 4. When inf dications of a preselected remote object are only desired, antenna |0 is rotated through an angle enclosing such object, as shown in Fig. 4.

There is thus provided by the present inVention a radio echo apparatus capable of producing a plan position indication of all remote objects included within a field extending 360 about the` apparatus and for only producing an indication ofthe remote objects included within'a portion of the area extending 360 about the apparatus.

The latter means includes novel devices for p'ro" ducing an expanded plan position indication on the entire area ofthe cathode ray indicator tube screen of any preselected portion or sector ofthe plan position indication of the area extending? 360 about the apparatus. With an arrange` ment having the foregoing characteristicarange and directional indications of remote objects'V corresponding to the echo pulse indications in'A eluded within the expanded plan position indication are obtained with greatly increased ac-fV curacy.

.Although only one embodiment of the uwen; tion has been disclosed and described herein it' is to be expressly understood that" various changes and substitutions may be made therein without departing from the spirit of theji'nven-'- tion as well understood by those skilledvin the' art. Reference therefore will be had to the api-A pended claims as a definition of the limits'of the invention. A

The invention described herein maybe manu-` factured and used by or for the Government of the United States of America for governmentalL purposes without the payment of any royalties thereon or. therefor.

What is claimed is:

1. In an apparatus for determining range of'v remote objects, means scanningl an area-with asource of directional energy, means receiving' energy reflected from remote objects whenever said directional energy impinges upon remoteobjects, indicating means including an indicating area, means controlling the indicating means responsively to the received energy toproducevon the indicating area an indication of there-l mote objects included within the scanned area,

means selecting a portion of said indication foriA presentation only on said indicating area andi are adjusted 1n such `a manner asi. toimaintam meansexpanding said portion to increase the acl* ject is represented by an indication at an angle from a center point corresponding to its azimuth angle with respect to the position of the exploratory means and at a distance from said center point which is proportional to the objects distance from said exploratory means, means for expanding a portion of said pattern which includes means for displacing the center point of said pattern from the center point of the indicator and means for expanding the radial sweep of said indicating means whereby a desired portion of said pattern in expanded to provide a more detailed view thereof.

11. The arrangement of claim l and means for oscillating the exploratory beam of said system through that portion of a complete revolution only for which an expanded pattern is desired.

12. An apparatus for determining range and azimuth of remote objects comprising indicating means including an indicating area, means producing control signals characteristic of the range and azimuth of all remote objects included within a field extending 360 about a reference point, control means for the indicating means operative responsively to the control signals to produce a plan position indication on the indicating area of all remote objects included within said field, selectively operable means controlling said indicating means to select a portion of said plan position indication for presentation only on said indicating area, and means expanding said portion to increase the accuracy of the range and azimuth indications provided thereby.

13. In an echo ranging device, an impulse `transmitter adapted to emit a recurrent energy impulse, a receiver for receiving the reflections of said energy impulses, a cathode ray tube indicator means coupled to the output of said receiver for indicating the receipt of said energy reflections, saw-tooth wave sweep generator means coupled to said indicator means and synchronized with said transmitter for producing a substantially uniform relatively slow speed trace of the electron beam of said indicator operable to spatially distribute in a uniform manner according to time of receipt substantially all the energy reflections received during the interval between successive impulses, sweep control means for said saw-tooth wave generator means for altering said slow speed trace to produce a substantially uniform high speed trace of the electron beam of said indicator, and means rendering said high speed sweep trace visible on the screen of said indicator only during a portion of the interval between successive impulses whereby only those impulses received coincident with said portion are indicated.

14. In an echo ranging device, an impulse transmitter adapted to emit a recurrent energy impulse, a receiver for receiving the reflections of said energy impulses, a cathode ray tube indicator means coupled to the output of said receiver for indicating the receipt of said energy reflections, saw-tooth wave sweep generator means coupled to said indicator means and synchronized with said transmitter for producing a substantially uniform relatively slow speed trace of the electron beam of said indicator operable to spatially distribute in a uniform manner according to time of receipt substantially all the energy reections received during the interval between successive impulses, sweep control means for said saw-tooth wave generator means for altering said slow speed trace to produce a substantially uniform high speed trace of the electron beam of said indicator, means rendering said high speed sweep trace visible on the screen of said indicator only during a portion of the interval between successive impulses whereby only those impulses received coincident with said portion are indicated, and means operable to selectively control the time of occurrence of said portion in the interval between pulses.

15. Apparatus for recurrent signal analysis comprising, a cathode ray tube indicator means adapted to receive and visually display the signal to be analyzed, time base generator means synchronized with the recurrent signal to be analyzed coupled to said indicator for producing a substantially uniform relatively slow speed time base of the electron beam of said indicator operable to spatially distribute in a uniform manner according to occurrence time substantially all the signal elements which comprise the signal to be analyzed, time base control means for said time base generator means for altering said slow speed time base to produce a substantially uniform high speed time base of the electron beam of said indicator, and means rendering said high speed time base visible on said indicator only during a small portion of the signal being analyzed whereby only those signal elements coincident with said portion are indicated.

16. Apparatus for recurrent signal analysis i comprising, a cathode ray tube indicator means adapted to receive and visually display the signal to be analyzed, time base generator means synchronized with the recurrent signal to be analyzed coupled to said indicator for producing a substantially uniform relatively slow speed time base of the electron beam of said indicator operable to spatially distribute in a uniform manner according to occurrence time substantially all the signal elements which comprise the signal to be analyzed, time base control means for said time base generator means for altering said slow speed time base to produce a substantially uniform high speed time base of the electron beam of said indicator, means rendering said high speed time base visible on said indicator only during a small portion of the signal being analyzed whereby only those signal elements coincident with said portion are indicated, and means operable to selectively control the time of occurrence of said portion during the occurrence of the signal to be analyzed.

' ROBERT M. PAGE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENT 

